Discrete commodity handling has become increasingly important in the information age. Presently, computer processing and telecommunication technology enable businesses to explore the global marketplace, often processing orders for products from distant markets in a matter of seconds. However, such international market access, while theoretically broadening the product market, is often limited by the logistical challenges presented in moving a product from producer to international consumer.
The logistical process utilized by industries to hasten the response to this seemingly instantaneous demand has been through the streamlining of their internal production and shipping practices. One tool utilized by industry to effectuate such streamlining is roller bed conveyor technology. Conveyor technology has grown from the basic inclined bed of skate wheel rollers in which products are propelled by their own inertia or simple gravity, to multi-level computer-controlled delivery systems. Automated conveyors in particular offer industry the ability to move and channel articles in bulk to any location within a facility quickly, offering substantial reduction in time and labor.
Automated conveyor systems such as U.S. Pat. No. 5,211,281 and U.S. Pat. No. 4,266,659 exemplify the type of frictional drive means common throughout the industry. Typically, a frictional sheet belt comprised of rubber or similar material is utilized to drive a plurality of skate wheel rollers. Despite the technological advances in "smart" accumulating conveyor control, modular conveyors etc., the dependability of such automated conveyors is in large part a function of their drive system.
The present state of the art in automated roller bed conveyor drives suffers from the drawbacks of the present frictional drive configuration. Specifically, the frictional drive belt element has a lifespan naturally limited by the loading and usage of the conveyor roller bed, but as often the case with the present configuration, uneven loading decreases the lifespan of the frictional drive belt by increasing the wearout rate and necessitating more frequent belt replacement. Moreover, uneven loading in conveyors utilizing the present configuration is likely to demand careful alignment and/or special devices such as idler rollers, pulleys, etc. to insure proper tracking of the frictional belt over the free moving caster rollers. Mistracking is further aggravated when uneven loading of the belt occurs, as when products accumulate more on one or the other side of the belt.
Decreased lifespan of drive belts due to premature wear necessitates simple belt replacement. However in high volume industries, particularly those with multiple conveyer tracks, such repeated loss of distribution capacity or "down time" frustrates the sole purpose of the system by further delaying product processing. Similarly, belt slippage and mistracking further frustrates the purpose of efficient and cost effective product processing by increasing the risk of product damage. Unpredictable drive forces may impel closely placed products together, damaging precision and fragile products, if not jolting them from the conveyor bed altogether.
The utilization of tracking and belt guidance mechanisms in the art has in some cases decreased belt wear and mistracking at the expense of overall conveyor reliability through the introduction of this additional system hardware.
Presently, an automated conveyor drive design is desired which offers the traditional components of frictional drive systems, that is, frictional conveyor bed coupling in a low cost belt design, but having the added feature of increased belt reliability absent the added requirement of belt guidance hardware.
A current drive system replaces the conventional belt with a chain having a drive pad mounted along one side of the chain. The chain has a run which extends along the length of the roller bed where the rollers are to be driven such that the drive pad frictionally engages the rollers to rotate them as the chain is advanced along the roller bed. The driver pad is subject to wear, damage, and/or contamination, and it must be replaced after intervals of use.